This invention relates to mobile crop harvesters for harvesting hay or forage, such as a mower conditioner or windrower of the type having a laterally elongated crop harvesting header mounted by a linkage to a carrying frame and, more particulary, to a lift and float mechanism for controlling the linkage to move the header between a lowered operating position and a raised transport position.
It is previously known to provide floatation spring and lift linkages acting upon the lower swing links interconnecting a crop harvesting header to a windrower carrying frame. See, for example, Schoeneberger U.S. Pat. No. 3,958,399, which teaches a lift and float mechanism similar to that described herein.
It has been found however, that certain improvements can be made in the lift and float mechanism which will improve the operation, appearance, and durability of a mower conditioner. For example, one problem encountered is that when the header floats upwardly relative to the carrier frame, the floatation springs become weaker and therefore some of the counterbalancing force is lost.
Accordingly, it is an object of the invention described and claimed herein to dispose the pivotal connection of the floatation springs to the lower spring link substantially below the pivot of the swing link with the frame.
A further object of the invention is to dispose the header lift cylinders wholly within the carrying frame of the harvester which not only protects the cylinders from injury from external sources but also improves the appearance of the machine.
The above objects are met in a mobile crop harvester comprising a wheel supported main frame including a pair of hollow generally vertical laterally disposed frame members and a horizontal beam extending laterally between said vertical frame members, an elongated crop harvesting header mounted to said frame by a pivotal linkage including an upper link and a pair of laterally disposed lower swing links for movements of the header between a lowered operating position and a raised transport position, said header further comprising a cutting apparatus disposed across the forward edge thereof and ground shoes for engaging the height of the cutting apparatus in the operating position. The lifting apparatus comprises a lifting strap pivotally attached to each of the lower links intermediate the ends thereof at a point below a line interconnecting the pivotal mountings of the lower link and below the pivotal mounting thereof to the frame in the operating position. The lifting strap extends upwardly to a lift lever arm pivotally mounted wholly within the vertical frame member and having a lost motion connection with the lifting strap and a hydraulic cylinder, pivotally mounted wholly within the vertical frame member, is pivotally attached to the lifting arm so that upon extension, the hydraulic cylinder takes up the lost motion connection and lifts the lower link through the lifting strap. Floatation springs are attached to the lower portion of the lifting strap in laterally adjacent relationship and extend upwardly to adjustable connections with the frame member.